2001 Yamaha Bear Tracker..I bought it used but was very well taken care of, low hours and owned by an older fellow who just used it to ride around on his property occasionally. It was running great and all of a sudden began to sputter and backfire. It would start first time but only idle, could not open the throttle at all without dying. I cleaned the carb several times, put a kit in the carb. I checked for leaks in the intake and exhaust. Then I replaced the ignition coil but same situation. I purchased a new stator assembly and installed it, then had no fire at all. I put the old stator back in the bike and it started up but had the same problem I started with. I read in some blog where a person had installed a new stator and had to reverse the two wires on the pickup coil. I removed the pickup coil from the new stator and reversed the wires and it fired up and ran pretty good for awhile, didnt have the jump that it used to and would occasionally backfire and sputter but just occasionally. I had purchased a spark tester from an auto shop, which is a light that goes between the spark plug and the plug wire from the coil. I have noticed that when the bike is not taking throttle that the light on the tester will dim when I open the throttle and is described by the tester instructions to be something faulty in the ignition. I noticed that when the bike would die, while using the tester, that the light would still glow after the engine had died for 10 to 15 seconds. I was riding it yesterday and it would sputter on occasion, then started backfiring and dyed. The engine was not running, but the ignition switch was still on, I reached down to make sure I had a good connection with the spark plug and the plug wire and it shocked the fool out of me. Could a bad CDI module do this? I had installed the old ignition coil back on the bike because the aftermarket one I had bought looked much cheaper, so I thought it may have been breaking down, but unless I have ended up with two bad ignition coils, there must be another problem....any ideas?

 

Possible bad spark plug wire? You can take a spray bottle with water and spray a fine mist around the plug wire in the dark with the engine running, and look for arcing. That's how I found a bad plug wire on an old VW once upon a time.

 

hey I know this is super old. But I'm having the exact same issue with my bear tracker. Hoping you found and can remember the solution?